Joystick control systems have been widely used in a variety of applications where it has been required to move an object in a plane. Such applications include systems for controlling the movement of mechanical devices, such as tracked vehicles or wheelchairs to the widely used systems for controlling the position or movement of a visual image on the face of a CRT.
In general, the known joystick control system can be divided into two types. The first is an electrical contact system wherein the mechanical movement of the joystick is converted into electrical control signals via a series of electrical contacts or switches. The second is a potentiometer type system wherein a potentiometer, moveable in conjunction with the joystick, is positioned on at least two axis of rotation and the chaning resistance of the potentiometers generate electrical control signals.
The systems which utilize electrical contacts, or in some cases electrical switches, suffer from several disadvantages. First is the limited life of any electrical contact resulting from a dirty environment, shock and misalignment. This problem is particularly acute in the exploding video game industry wherein overzealous video game jockeys, enthralled with the "action" on the screen, routinely destroy joustick controllers resulting in expensive replacement costs and excessive down-time for the video game.
Another problem with such devices is their inherent nonlinear nature. That is, changes in position of the joystick are communicated to associated control circuitry as contact is made with a plurality of separate contacts or switches. A small number of separate contacts or switches has the advantage of low cost and increased reliability, but the large changes in movement between successive contacts results in sudden and jerky movement of the object or visual image being controlled. Alternatively, use of a large number of contacts, or switches, will "smooth out" the action, but this, of course, raises the cost of the device and reduces its reliability due to the increase in possible points of failure.
It is, therefore, another object of the instant invention to provide a low cost joystick control system without the inherent disadvantages of known electrical contact systems.
It is another object of the instant invention to provide a joystick control system with increased proportionality between joystick movement and movement of the object being controlled without increasing the costs, or reducing the reliability of the control system.
Potentiometer type joysticks are preferred in that they provide a continuous control signal rather than discrete signal changes as are inherhent with contact type joysticks. For this reason, potentiometer type joysticks are generally used in more expensive and complicated systems for controlling the movement of images on a CRT. Although potentiometer type systems overcome some of the problems associated with electrical contact syste, they still have inherent disadvantages. The foremost disadvantage is the cost of the potemtiometers, the additional moving parts and attendant lower reliability. Also, of course, any potentiometer is vulnerable to a dirty environment which can make the control system unworkable.
It is, therefore, a still further object of the instant invention to provide a joystick control system that does not require the use of potentiometers for operation.
It is still another object of the instant invention to provide a high quality, low cost, joystick control system that is highly reliable and readily manufactured for a wide variety of applications.